1. Preheat oven to 400°. Place fish on a baking sheet and bake for 15 minutes or until well browned and fish flakes easily.

2. Meanwhile, cook spinach according to package directions with celery added; cook until celery is crisp-tender. Press spinach-celery mixture against the sides of a sieve with a rubber scraper to remove excess moisture. Return spinach to saucepan.

5. Spread spinach mixture evenly in an ungreased shallow 1-quart casserole. Top with fish. Spoon reserved white sauce over fish without completely covering fish. Top with cheese in a decorative pattern and sprinkle with bacon bits. Bake for 3 to 5 minutes or until cheese melts.

3. Mash potatoes until no lumps remain. Beat in milk in small amounts (amount of milk needed to make potatoes smooth and fluffy depends on kind of potatoes). Add 1/2 cup margarine, the salt and pepper. Beat vigorously until potatoes are light and fluffy. Add eggs; beat until blended.

4. Drop potato mixture by 12 spoonfuls into mounds onto cookie sheet. Or place in decorating bag with star tip and form rosettes or pipe a border around meat or fish. Brush with melted margarine. Bake about 15 minutes or until light brown.